Modern military vessels typically carry weapons such as unmanned aerial vehicles, missiles or cruise missiles that are jet powered and launched from a vessel at high speeds. Missions for such missiles can be planned in its totality on the ground, so called pre-planned missions. It can also be planned partially or entirely in the air while being carried by an aircraft. This is often called re-planning or re-targeting in the first case and a so called target of opportunity in the second case. It is also well known that the functionality of mission planning in the latter two cases can be performed on board a missile.
The paper titled “Mission Planning Technology” by Erik Berglund (June, 2001, RTO-EN-018) touches on the subjects mission planning and re-planning for missiles during flight. It is however only mentioned that this is possible due to technological advances without mentioning how mission planning is performed.
Boeing has developed a system called SLAM ER with an ability to attack a land-based target of opportunity. The system has a target-of-opportunity mode allowing a pilot to send target coordinates to the missile on a wing of an aircraft prior to launch. After launch, the missile flies toward the target location and provides infrared seeker video back to the control aircraft for standoff and man-in-the-loop terminal control. This can be used for re-planning by redirecting missions for avoiding unexpected targets such as missile launchers, or direct a missile to a secondary target after primary targets are destroyed.
DE-102006007142 A1 describes a method for positioning an unmanned missile. Target data are transferred to a missile prior to launch, and mission planning is performed in the missile.
A second functionality that is well known is the so called Time on Target feature. This consists in the capability of the cruise missile to arrive at a designated target at a designated time when told to do so. This opens up the possibility to have two or more missiles arriving at the same (or different or slightly different) target at the same time (a so called salvo or ripple mission) and in this way trying to overwhelm the defense mechanisms of the target. A typical target in such a case can be a well defended ship or a strategically important ground-based target.
When a salvo mission for a group of air launched cruise missiles is planned on the ground well before the designated Time on Target, it poses the problem of having to plan a very exact time of launch of all the participating missiles well into the future. If one or more aircraft should fail to reach its area of launch in time, there will be a risk for the whole mission. A re-planning of the mission demands the capability to communicate the totality of the mission from a central computing machine. Re-planning communication can be sent from some land-based station or from one of the airplanes taking part in the mission. The kind of computing and transmission capabilities necessary for performing a re-planning is however not common for an aircraft. The bandwidth required for the communication between an airplane and missiles is not ordinarily available in the air.
To solve this and to allow for a target of opportunity type of mission, one can use the mission planning capabilities of modern missiles. According to the present invention planning or re-planning a salvo mission in the air is performed by letting all missiles plan the exact same mission. In this way they will all have routes that allow them to reach to the same target at the same time or approximately the same time. The problem with this solution is however that there is a high risk of interference and impact between the missiles as they will all try to travel the same route at the same time. The present invention describes a way of overcoming this problem.